Low-loss silicon-based hybrid plasmonic waveguide with an air nanotrench for sub-wavelength mode confinement

A hybrid plasmonic waveguide based on a silicon-on-insulator substrate with an air trench is proposed and investigated. Theoretical analysis demonstrates that the nano-scale air trench could result in strong local field enhancement and tight mode confinement. Besides, the transmission loss of the fundamental hybrid plasmonic mode could also be reduced despite the existence of the high-index silicon rib. The proposed structure is compatible with standard nanofabrication process based on the silicon wafers and could enable various nanophotonic integrated components.